A team of Cornell University scientists from the College of Veterinary Medicine, Weill Cornell Medical College and the College of Agriculture and Life Sciences have discovered that a novel group of E. coli bacteria -- containing genes similar to those described in uropathogenic and avian pathogenic E. coli and enteropathogenic bacteria such as salmonella, cholera, bubonic plague -- is associated with intestinal inflammation in patients with Crohn's disease.
Crohn's disease, an incurable inflammatory disorder of the intestine -- most commonly found in the lower part of the small intestine called the ileum -- affects 1-in-1,000 people in Europe and North America. Thus far, gut bacteria have long been suspected in playing a pivotal role in the development of Crohn's disease, but the specific bacterial characteristics that drive the inflammatory response have remained elusive.
Researchers at Cornell examined possible causes for the disease in patients with Crohn's restricted to the ileum and the colon versus healthy individuals.
"Given that only about 20 percent of fecal bacteria can be cultured, our group adopted a broad culture-independent approach to target specific subgroups of bacteria for quantitative in situ analysis and culture based characterization," said Kenneth Simpson, professor of small animal medicine at the College of Veterinary Medicine.
"Our findings raise the possibility that a novel group of E. coli contains opportunistic pathogens that may be causally related to chronic intestinal inflammation in susceptible individuals. They suggest that an integrated approach that considers an individual's mucosa-associated flora in addition to disease phenotype and genotype may improve outcome."
The study found an increased level of E. coli bacteria in more inflamed areas of the small intestines instead of MAP, a bacterium related to tubercle bacillus that has been more commonly associated with Crohn's.
Reference: "Culture independent analysis of ileal mucosa reveals a selective increase in invasive Escherichia coli of novel phylogeny relative to depletion of Clostridiales in Crohn's disease involving the ileum" The ISME Journal: Multidisciplinary Journal of Microbial Ecology, July 12, 2007
The study was supported by an Ithaca Cornell-Weill Cornell Seed Grant.
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